1. Field of the Invention
The present invention relates to a molding method and a molding apparatus for a laminated molded body such as insulator dashboards of cars.
2. Description of the Prior Art
Ordinarily, an insulator dashboard having sound insulation function is installed on a dashboard panel facing a car interior, with the dashboard panel placed in front of the driver seat and the passenger seat of a car. The dashboard panel is made of a laminated molded body of a sound insulation material such as a thermoplastic resin sheet and a sound absorption material such as felt and polyurethane foam.
Conventional molding method for the insulator dashboard will be explained on the basis of the drawings of FIG. 19 and FIG. 20.
First, sound absorbing material is heated to 165 to 175.degree. C. measured at its surface through a hot blast heating furnace, the hot material is shaped to its desired shape by cold pressing step and the sound absorption material shaped is cooled, and the material is molded to its precise shape of the dashboard.
Next, as shown in FIG. 19, the sound absorption material 1 of desired shape is set on a lower mold 3 for cold-pressing-molding, and a sound insulating material 2 heated to 130 through 135.degree. C. measured at its surface is placed on the sound absorbing material 1. A cold-pressing-molding upper mold 4 having substantially the same shape or profile as that of the cold-pressing-molding lower mold 3 is placed above the lower mold 3.
Next, as shown in FIG. 20, the cold pressing molding upper mold 4 is lowered, a pressing pressure of 15 to 30 kg/cm.sup.2 is applied between the lower mold 3 and the upper mold 4 for in order to mold the sound absorbing material 1 and the sound insulation material 2, a predetermined cooling period is elapsed, a second pressing (pressure: 100 to 150 kg/cm.sup.2) is done in order to trim or cut the circumference or the outer periphery of the product by means of trimming blade 8 provided around the circumference of the cold-pressing-molding upper mold 4.
Then, a water-jet cutting device or special purpose mold is used to carry out a trimming or piecing the process completing the molding of products.
According to the conventional molding method for insulator dashboards, after the sound absorbing material 1 is shaped in a desired shape by means of a press mold, a different press mold is used to press the sound insulation material 2 and the sound absorbing material 1, so that it is necessary to employ two steps of pressing and to prepare plural mold installations.
In addition, it has been difficult to control the pressure level in pressing of the sound insulation material 2 and the sound absorbing material 1. When the pressure level is too high, the sound absorbing material 1 may be crushed the resulting in failure of obtaining appropriate thickness of the product. On the contrary, if pressure level is too weak, one of the sound insulation material 2 and the sound absorbing material 1 may be peeled from other one.
Still, according to the prior art, the elasticity of the sound absorption material 1 prevents the pressing pressure from being appropriately transferred to the sound insulation material 2, making it difficult to precisely or sharply shape the of corners of the product.
Additionally, the sound absorbing material 1 is typically made of a thermal-molded felt having thermal insulation quality. Thus, it takes a long time to cool the molded sound absorbing material 1, requiring a longer molding cycle.